The invention relates to a method and device for decoupling mass for a motor vehicle.
One of the most significant trends is the electrification of transportation, in particular of road vehicles. Vehicles are increasingly being driven by means of an electric motor or by means of a combination of an electric motor and an internal combustion engine. The electric energy required for this purpose is stored in an electrical energy store, which is installed on board the vehicle. Hence, the importance of electrical on-board technology is also increasingly an important prerequisite for this development. Growing demands with regard to safety technology involve the development of increasingly more complex crash constructions and systems. In the case of electric and so-called hybrid vehicles, the problem of the contribution of the vehicle battery to a crash balance as well as the safeguarding of the battery as a relatively expensive component additionally arises.
In this case, the electrically driven vehicles have the greatest importance. In order to achieve a large cruising range, said electrically driven vehicles are equipped with batteries which have a mass of several hundred kilograms. The proportion of the battery mass of the total mass in known electric vehicles typically amounts to 30% and thus comprises a disproportionally high percentage. In light of the fact that the energy density of batteries will not achieve the level of energy density of conventional fuels in the foreseeable future, the relatively high mass thereof is a safety factor. There is thus a growing need for protective devices and measures, by means of which the vehicle passengers, the battery and also the vehicle can be accordingly protected. The way in which the battery is mounted to the body of the motor vehicle is therefore of great importance. Known concepts for electrically driven vehicles intend for the battery to be a coherent rigid block having a center of mass set as deeply as possible in the region of the underbody of the vehicle between the front and rear axle. The battery together with the support structure thereof also influences the rigidity of the passenger compartment.
During a collision of the vehicle, the mass modules, i.e. passengers, luggage and battery are exposed to an impulse-like acceleration. The mass components active respectively at a certain point in time, the relative kinematics thereof and the energetic component of the total balance of the kinetic energy are decisive for the respective acceleration-time curve of a module.
The German patent DE 10 2012 204 856 A1 discloses a mass-coupling arrangement for a vehicle. By means of an elastic and controllable connection system between mass components of the vehicle, it is possible to actively influence the accelerations of mass units in a certain period of time during a vehicle collision. As a result, the effective loads on the passengers and on the battery are adjusted, i.e. not the entire vehicle mass but only a certain mass component in the defined period of time. For example, it is possible to temporarily mechanically decouple the battery including the support structure thereof from the vehicle. By exerting this influence, the battery mass passes through its own movement trajectory during a collision, and ultimately a more favorable temporal configuration of the partial crash pulses of the proportional masses and the loads working thereupon is achieved.